Combination read/write thin film magnetic head using a shielding magnetic layer

ABSTRACT

The present invention provides a combination read/write thin film magnetic head wherein the width of a gap layer is the same as the track width Tw, and a shielding magnetic layer of a soft magnetic material is formed on both sides of the gap layer so that blots of a record magnetic field out of the track width Tw can be absorbed by the shielding magnetic layer, and write fringing can be prevented. Particularly, when the saturation magnetic flux density and thickness of the shielding magnetic layer are appropriately adjusted, it is possible to suppress write fringing, and at the same time maintain reproduced output at a high level.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a combination read/write thin filmmagnetic head used as a floating type magnetic head, and particularly toa combination read/write thin film magnetic head in which a shieldingmagnetic layer is provided on either side of a magnetic gap of aninductive thin film magnetic head in the direction of the track widththereof in order to suppress the occurrence of write fringing, and amanufacturing method thereof.

2. Description of the Related Art

FIG. 17 is a perspective view schematically showing the whole structureof a conventional combination read/write thin film magnetic head formedon a slider 10, and FIG. 18(a) is a partial front view showing theconventional combination read/write thin film magnetic head, as viewedfrom the side opposite to a recording medium.

The combination read/write thin film magnetic head shown in FIGS. 17 and18(a) is formed at the trailing end of the slider 10 which constitutes afloating type head, and comprises a laminate of a reading head h1 and arecording inductive head h2.

The combination read/write thin film magnetic head further comprises alower core layer 11 made of a magnetic material having high magneticpermeability, such as an Ni-Fe alloy (permalloy), sendust, or the like.In the combination read/write thin film magnetic head comprising thereading head h1 which employs a magnetoresistive element, and theinductive head h2 which is continuously laminated thereon, the lowercore layer 11 functions not only as a core layer for the inductive headh2 but also as an upper shielding layer for the reading head h1.

On the lower core layer 11 is formed a gap layer 12 made of anon-magnetic material such as Al₂ O₃ (alumina) or the like. On the gaplayer 12 is formed an insulation layer (not shown in the drawings) madeof a resist material such as polyimide or the like or another organicmaterial. On the insulation layer is spirally formed a coil layer 5using an electrically conductive material having low electricresistance, such as Cu or the like. The coil layer 5 is formed so as toturn round the base end 3b of an upper core layer 3.

On the coil layer 5 is formed an insulation layer (not shown in thedrawings) made of an organic resin material or the like. On theinsulation layer is formed the upper core layer 3 by plating a magneticlayer such as permalloy or the like. In a portion opposite to themagnetic medium, the tip 3a of the upper core layer 3 is joined to thelower core layer 11 with the gap layer 12 therebetween to form amagnetic gap having a gap length G1. The base end 3b of the upper corelayer 3 is magnetically connected to the lower core layer 11.

In the writing inductive head h2, when a recording current is suppliedto the coil layer 5, a record magnetic field is induced in the lowercore layer 11 and the upper core layer 3, and a magnetic signal isrecorded in the recording medium such as a hard disk or the like by aleakage magnetic field from the magnetic gap portion between the lowercore layer 11 and the tip 3a of the upper core layer 3.

In the writing magnetic gap of the inductive head h2, the gap length G1is determined by the distance (i.e., the thickness of the gap layer 12)between the lower core layer 11 and the tip 3a of the upper core layer 3joined thereto with the gap layer 12 therebetween. As shown in FIG.18(a), the track width Tw is determined by the width of the tip 3a ofthe upper core layer 3.

As shown in FIG. 18(a), the width T2 of the lower core layer 11 issufficiently larger than the width Tw of the tip 3a of the upper corelayer 3. The reason why the width T2 of the lower core layer 11 islarger is that the area of the upper flat surface of the upper corelayer 11 is increased to facilitate the formation of the coil layer 5 onthe lower core layer 11 with the insulation layer therebetween, and atthe same time, to increase the magnetic shielding effect on themagnetoresistive element layer 13 formed below the inductive head h2.

In the reading head h1 which employs magnetoresistance, themagnetoresistive element layer 13 is provided on a lower shielding layer14 with a lower gap layer 15a therebetween, and the lower core layer 11is formed on the magnetoresistive element layer 13 with an upper gaplayer 15b therebetween, the magnetoresistive element layer 13 alsoserving as an upper shielding layer.

If the width T2 of the lower core layer 11 is larger than the width Twof the tip 3a of the upper core layer 3, as shown in FIG. 8(a), when arecord magnetic field is induced in the lower core layer 11 and theupper core layer 3, and a recording leakage magnetic field is generatedbetween the tip 3a and the lower core layer 11, the leakage magneticfield is beyond the range of the width (track width ) Tw of the tip 3aof the upper core layer 3, and affected by the width of the lower corelayer 11 to bring about blots of the magnetic field on both sides of thewidth Tw.

FIG. 18(b) shows a recording pattern of the data recorded by using themagnetic head shown in FIG. 18(a). The recording pattern indicates thatwrite fringing (writing blot) occurs out of the track width Tw. Theoccurrence of this write fringing makes it impossible to detect thetrack position on the written recording medium with high precision, andthus causes tracking servo error. Particularly, in high-densityrecording, the pitch of adjacent tracks is small, and thus writefringing has a significant effect.

SUMMARY OF THE INVENTION

An object of the present invention is to solve the problems of priorart, and provide a combination read/write magnetic head comprising ashielding magnetic layer provided on either side of a gap layer and madeof the same soft magnetic material as a lower core layer or another softmagnetic material in order to sufficiently suppress write fringing,without deteriorating over write performance during recording, and amanufacturing method thereof.

In order to achieve the object, the present invention provides acombination read/write thin film magnetic head comprising a lower corelayer of a magnetic material, an upper core layer of a magnetic materialprovided opposite to the lower core layer and having a width smallerthan that of the lower core layer, a gap layer provided between thelower core layer and the upper core layer, a coil layer for inducing arecord magnetic field in the lower core layer and the upper core layer,a non-magnetic material layer formed on the lower core layer to form thegap layer by the non-magnetic material layer between the lower corelayer and the upper core layer, and a shielding magnetic layer of a softmagnetic material provided to cover either side of the gap layer in thedirection of the track width.

In the magnetic head, the width Tw of the upper core layer in thedirection of the track width, the width of the upper surface of the gaplayer which contacts the upper core layer and the width T1 of the lowersurface of the gap layer which contacts the lower core layer may be thesame.

In the present invention, the non-magnetic material layer on both sidesof the magnetic gap layer is removed by plasma etching, leaving as amagnetic gap layer a portion of the non-magnetic material layer heldbetween the lower core layer side and the upper core layer so that thewidth Tw of the upper core layer, the width of the upper surface of thenon-magnetic material layer which contacts the upper core layer, and thewidth T1 of the lower surface of the non-magnetic material layer whichcontacts the lower core layer can be the same, as shown in FIGS. 1, 2,3, 6 and 8.

The present invention also provides a combination read/write thin filmmagnetic head having a shape in which the width of the gap layer in thedirection of the track width gradually increases from the upper surfacewhich contacts the upper core layer to the lower surface which contactsthe lower core layer. This is shown in, for example, FIGS. 4, 5 and 7.

The shielding magnetic layer is formed by, for example, removing aportion of the non-magnetic material layer where the lower core layerand the upper core layer are not opposite to each other, by ion-milling.When a portion of the non-magnetic material layer is removed byion-milling, both sides of the gap layer in the direction of the trackwidth are made inclined surfaces which extend toward the lower corelayer.

The average thickness L1 of the shielding magnetic layer is preferablywithin the range of 0.001 to 1.0 μm.

When the shielding magnetic layer has a saturation magnetic flux densityBs of 0.95 T or less, the thickness L1 of the shielding magnetic layeris preferably within the range of 0.05 to 1.0 μm.

Examples of soft magnetic materials having a saturation magnetic fluxdensity of 0.95 T or less include Ni-Fe alloys (Bs=0.95 T), Co-Zr-Nballoys (Bs=0.5 T), and the like.

For example, when the shielding magnetic layer is made of a Ni-Fe(nickel-iron) alloy, the thickness L1 of the shielding magnetic layer ispreferably within the range of 0.05 to 0.48 μm, more preferably 0.05 to0.38 μm or 0.05 to 0.4 μm.

When the shielding magnetic layer is made of a Co-Zr-Nb(cobalt-zirconium-niobium) alloy, the thickness of the shieldingmagnetic layer is more preferably within the range of 0.2 to 0.73 μm.

When the saturation magnetic flux density Bs of the shielding magneticlayer is 0.95 to 1.8 T, the thickness L1 of the shielding magnetic layeris preferably within the range of 0.01 to 0.4 μm. When the saturationmagnetic flux density Bs of the shielding magnetic layer is 1.8 T ormore, the thickness L1 of the shielding magnetic layer is preferablywithin the range of 0.001 to 0.4 μm.

Examples of soft magnetic materials having a saturation magnetic fluxdensity Bs of 0.95 T or more include the above Ni-Fe alloys, Co-Fe-Nialloys (Bs=1.8 T), and the like.

When the shielding magnetic layer is made of a Co-Fe-Ni(cobalt-iron-nickel) alloy, the thickness L1 of the shielding magneticlayer is preferably within the range of 0.01 to 0.19 μm or 0.01 to 0.2μm.

A method of manufacturing the combination read/write thin film magnetichead of the present invention comprises the steps of:

forming the non-magnetic material layer on the lower core layer;

forming the upper core layer on the non-magnetic material layer;

forming the gap layer by removing a portion of the non-magnetic materiallayer where the lower core layer and the upper core layer are notopposite to each other, leaving the non-magnetic material layer betweenthe upper core layer and the lower core layer; and

forming the shielding magnetic layer of a soft magnetic material oneither side of the gap layer in the direction of the track width.

In the manufacturing method, when the non-magnetic material layer whichforms the gap layer is made of a material which can be removed by plasmaetching, a portion of the non-magnetic material layer is removed wherethe lower core layer and the upper core layer are not opposite to eachother. In this case, the upper surface of the gap layer which contactsthe upper core layer and the lower surface thereof which contacts thelower core layer have substantially the same width.

A portion of the non-magnetic material layer where the lower core layerand the upper core layer are not opposite to each other can also beremoved by ion-milling. In this case, both sides of the gap layer becomeinclined surfaces.

The shielding magnetic layer can be formed by a deposition process, butit can also be formed by readhering the magnetic material which isremoved from the lower core layer by ion-milling to both sides of thegap layer in the direction of the track width.

Examples of non-magnetic materials (the non-magnetic material forforming the gap layer) which can be removed by the plasma etchinginclude single layer films of SiO₂, Ta₂ O₅, Si₃ N₄, TiO, Ti₂ O₃, Ti₃ O₅,and TiO₂ ; composite films or multilayer films comprising at least twofilms thereof.

As the plasma etching, unidirectional plasma etching with CF₄ or CF₄ +O₂is used in which the non-magnetic material in a portion other than thegap layer interposed between the lower core layer and the upper corelayer is selectively removed. The unidirectional plasma etching causesno damage to the magnetic layers which respectively form the upper corelayer and the lower core layer.

In the step of removing the non-magnetic material layer by ion-milling,inclined portions are formed not only on both sides of the gap layer, asdescribed above, but also in the lower core layer by removing portionson both sides thereof because a soft magnetic material such as permalloyor the like which constitutes the lower core layer is readily affectedby the ion milling. As the ion-milling, milling with neutral ions ofargon gas is used.

As the method of forming the shielding magnetic layer of a soft magneticmaterial on either side of the gap layer, two methods can be provided,i.e., the method of depositing a soft magnetic material on both sides ofthe gap layer by sputtering or vaporization, and the method of partiallyremoving the lower core layer by ion-milling to readhere the removedsoft magnetic material to both sides of the gap layer.

Soft magnetic materials used for forming the shielding magnetic layer inthe present invention are given below.

(1. Crystal material)

(1) Ni-Fe alloy

(Composition) Soft magnetic alloys represented by the compositionformula Ni_(x) Fe_(y) wherein the composition ratios x and y by atomic %satisfy the relations, 86≦x≦92, 8≦y≦14 and x+y=100.

(2) Ni-Fe-Nb alloy

(Composition) Soft magnetic alloys represented by the compositionformula Ni_(x) Fe_(y) Nb_(z) wherein the composition ratios x, y and zby atomic % satisfy the relations, 76≦x≦84, 8≦y≦15, 5≦z≦12 andx+y+z=100.

(Effect) Decreasing an eddy current loss in high-frequency recording dueto high resistivity.

(3) Co-Fe alloy

(Composition) Soft magnetic alloys represented by the compositionformula Co_(x) Fe_(y) wherein the composition ratios x and y by atomic %satisfy the relations, 86≦x≦92, 8≦y≦14 and x+y=100.

(4) Co-Fe-Ni alloy

(Composition) Soft magnetic alloys represented by the compositionformula Co_(x) Fe_(y) Ni_(x) wherein the composition ratios x, y and zby atomic % satisfy the relations, 0.1≦x≦15, 39≦y≦62, 39≦z≦62 andx+y+z=100.

(5) Co-Fe-Ni-X alloy (X=Mo, Cr, Pd, B, In)

(Composition) Soft magnetic alloys represented by the compositionformula Co_(x) Fe_(y) Ni_(z) X_(w) wherein the composition ratios x, y,z and w by atomic % satisfy the relations, 0.1≦x≦15, 39≦y≦62, 39≦z≦62,0.05≦w≦15 and x+y+z+w=100.

(Effect) Decreasing an eddy current loss in high-frequency recording dueto high resistivity.

(2. Amorphous materials)

(1) Co-Zr-Nb amorphous alloy

(Composition) Amorphous soft magnetic alloys represented by thecomposition formula Co_(x) Zr_(y) Nb_(z) wherein the composition ratiosx, y and z by atomic % satisfy the relations, 1.5≦y≦13, 6.5≦z≦15,1≦y/z≦2.5 and x+y+z=100.

(2) Co-Hf-Ta amorphous alloy

(Composition) Amorphous soft magnetic alloys represented by thecomposition formula, Co_(x) Hf_(y) Ta_(z) wherein the composition ratiosx, y and z by atomic % satisfy the relations, 1.5≦y≦13, 6.5≦z≦15,1≦y/z≦2.5 and x+y+z=100.

(Effect) Permitting deposition of films having no unidirectionalmagnetocrystalline anisotropy, very high magnetic permeability andexcellent thermal resistance.

(3. Fine crystalline alloy)

(1) Fe-M-C alloy (M=Hf, Zr, Ti, V, Nb, Ta, Cr, Mo, W)

(Composition) Soft magnetic alloys comprising a crystal consisting of Feas a main component and a crystal of carbide or nitride of at least onemetal element selected from the group consisting of Hf, Zr, Ti, V, Nb,Ta, Cr, Mo and W, and as a whole, comprising fine crystals having a meangrain size of 40 nm or less, wherein if the mean grain size of thecarbide or nitride crystal is d, and the mean grain size of the crystalconsisting of Fe or Co as a main component is D, the d/D ratio is 0.05to 0.4, the composition formula is the following:

    Fe.sub.x M.sub.y C.sub.z

wherein M is at least one element of Hf, Zr, Ti, V, Nb, Ta, Cr, Mo andW, and the composition ratios (atomic %) satisfy the followingrelations:

    50≦x≦96, 2≦y≦30, 0.5≦z≦25 and x+y+z=100.

(2) Fe-X-M-C alloy

(Composition) Soft magnetic alloys having a texture basically comprisingfine crystal grains having a mean grain size of 0.08 m or less, andpartially containing a crystal phase of a carbide of an element, andrepresented by the following composition formula:

    Fe.sub.a X.sub.c M.sub.e C.sub.l

wherein X is at least one element of Al and Si, M is at least oneelement of Ti, Zr, Hf, V, Nb, Ta, Mo and W, and the composition ratios(atomic %) satisfy the following relations:

    50≦a≦95, 0.2≦c≦25, 2≦e≦25, 0.5≦l≦25 and a+c+e+l=100.

(3) T-X-M-Z-Q alloy

(Composition) Soft magnetic alloys comprising a crystal consisting of Feor Co as a main component and a crystal of carbide or nitride of atleast one metal element selected from the group consisting of Ti, Zr,Hf, V, Ta, Mo and W, and as a whole, comprising fine crystals having amean grain size of 40 nm or less, wherein if the mean grain size of thecarbide or nitride crystal is d, and the mean grain size of the crystalconsisting of Fe or Co as a main component is D, the d/D ratio is 0.05to 0.4, the composition formula is the following:

    T.sub.a X.sub.b M.sub.c Z.sub.e Q.sub.l

wherein T is at least one element of Fe and Co, X is at least oneelement of Si and Al, M is at least one metal element selected from thegroup consisting of Ti, Zr, Hf, V, Ta, Mo and W, Z is at least oneelement of C and N, Q is at least one metal element selected from thegroup consisting of Cr, Re, Ru, Rh, Ni, Pd, Pt and Au, and thecomposition ratios (atomic %) satisfy the following relations:

    40≦a≦98.5, 0≦b≦25, 1≦c≦10, 0.5≦e≦15, 0≦l≦10 and a+b+c+e+l=100.

(4) T-Si-Al-M-Z-Q alloy

(Composition) Soft magnetic alloys comprising a fine crystal having abody centered cubic structure consisting of Fe or Co as a main componentand a mean grain size of 40 nm or less, and a carbide or nitride of atleast one element of Ti, Zr, Hf, V and Ta which is precipitated in thegrain boundaries of the fine crystal, wherein at least one element ofCr, Ti, Mo, W, V, Re, Ru, Rh, Ni, Co, Pd, Pt and Au is dissolved in thebody centered cubic structure fine crystal, and the composition formulais the following:

    T.sub.a Si.sub.b Al.sub.c M.sub.d Z.sub.e Q.sub.l

wherein T is at least one element of Fe and Co, M is at least one of Zr,Hf, Nb and Ta, Z is at least one element of C and N, Q is at least onemetal element selected from the group consisting of Cr, Ti, Mo, W, V,Re, Ru, Rh, Ni, Pd, Pt and Au, and the composition ratios (atomic %)satisfy the following relations:

    40≦a≦90, 8≦b≦15, 0≦c≦10, 1≦d≦10, 1≦e≦10, 0≦l≦15 and a+b+c+d+e+l=100.

(Characteristic) Having a resistivity of 120 μΩcm or more, and a meangrain size of 40 nm or less.

(Effect) Having thermal stability and excellent acid resistance andcorrosion resistance, and permitting deposition of films having nounidirectional magnetocrystalline anisotropy.

(4. High-resistivity material)

(1) Fe-M-O (M=Hf, Zr, Ti, V, Nb, Ta, Cr, Mo, W)

(Composition) Soft magnetic alloys represented by the compositionformula Fe_(a) M_(b) O_(c) wherein M is at least one element of Hf, Zr,Ti, V, Nb, Ta, Cr, Mo and W, and the composition ratios a, b and c byatomic % satisfy the relations, 50≦a≦70, 5≦b≦30, 10≦c≦30 and a+b+c=100,having a resistivity of 400 to 2×10⁵ μΩcm, and comprising a mixture of abody centered cubic structure Fe fine crystalline phase having a meangrain size of 30 nm or less, and an amorphous phase containing much M orO, wherein the ratio of the body centered cubic structure Fe finecrystalline phase to the texture is 50 vol % or less.

(Characteristic) Comprising 50 vol % or more of amorphous phaseconsisting of M and O and containing the bcc Fe fine crystalline phasehaving a mean grain size of 30 nm or less.

(Effect) Causing a low eddy current loss in a high frequency region ofseveral tens MHz due to high resistivity (400 to 2×10⁵ μΩcm).

(2) Fe-M-N (M=a rare earth metal element, Hf, Zr, Ti, V, Nb, Ta or W)

(Composition) Soft magnetic alloys represented by the compositionformula Fe_(a) M_(b) N_(c) wherein M is at least one element of rareearth metal elements, Hf, Zr, Ti, V, Nb, Ta and W, and the compositionratios a, b and c by atomic % satisfy the relations, 60≦a≦80, 10≦b≦30,5≦c≦30 and a+b+c=100, and comprising a fine crystalline phase comprisinga body centered cubic structure Fe as a main component and having a meangrain size of 30 nm or less, and an amorphous phase comprising as a maincomponent a compound of N and at least one element M selected from thegroup consisting of the rare earth metal elements, Hf, Zr, Ti, V, Nb, Taand W, wherein the ratio of the amorphous phase to the texture is 50 vol% or more.

(Characteristic) Comprising 50 vol % or more of amorphous phaseconsisting of M and N and containing the bcc Fe fine crystalline phasehaving a mean grain size of 30 nm or less.

(Effect) Causing a low eddy current loss in a high frequency region ofseveral tens MHz due to high resistivity (400 to 2×10⁵ μΩcm).

(2) Fe-M-N (M=Hf, Zr, Ti, V, Nb, Ta or W)

(Composition) Soft magnetic alloys represented by the compositionformula Fe_(a) M_(b) N_(c) wherein M is at least one element of Hf, Zr,Ti, V, Nb, Ta and W, and the composition ratios a, b and c by atomic %satisfy the relations, 69≦a≦93, 2≦b≦15, 5≦c≦22 and a+b+c=100, andcomprising a fine crystalline phase comprising Fe as a main componentand having a mean grain size of 30 nm or less, and an amorphous phasecomprising as a main component a compound of N and at least one elementM selected from the group consisting of Hf, Zr, Ti, V, Nb, Ta and W.

(Characteristic) Comprising a mixture of the amorphous phase consistingof M and N, and the Fe crystalline phase having a mean grain size of 30nm or less.

(Effect) Causing a low eddy current loss in a high frequency region ofseveral tens MHz due to high resistivity (400 to 2×10⁵ μΩcm).

All of the above soft magnetic materials can be deposited by sputtering,but crystalline materials 1 of the soft magnetic materials can also beplated.

When the shielding magnetic layer is formed by sputtering, the softmagnetic material for forming the shielding magnetic layer may be thesame as or different from the soft magnetic material for forming thelower core layer.

When the shielding magnetic layer is formed by readhesion, a portion ofthe soft magnetic material which forms the lower core layer is removedby ion-milling, and the soft magnetic material removed is readhered tothe both sides of the gap layer. Therefore, the material of theshielding magnetic layer is the same as the lower core layer.

In the present invention, the gap layer is formed in the same width asthe upper core layer, and the shielding magnetic layer made of a softmagnetic material is provided either side of the gap layer. Thus, theleakage magnetic field out of the width Tw of the upper core layer isabsorbed by the shielding magnetic layer, thereby decreasing the amountof writing blot out of the track width Tw and suppressing writefringing.

Particularly, in formation of the shielding magnetic layer, when thesaturation magnetic flux density Bs and the thickness L1 thereof areappropriately adjusted, it is possible to suppress write fringing and atthe same time, maintain over write performance at a high level inrecording.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a half-sectional perspective view showing the shapes of alower core layer and an upper core layer of a combination read/writethin film magnetic head of the present invention;

FIG. 2 is a sectional view showing the structure of a combinationread/write thin film magnetic head of the present invention;

FIG. 3 is a partially enlarged front view as viewed from an arrow II ofFIG. 2;

FIG. 4 is a partially enlarged front view of a combination read/writethin film magnetic head in accordance with a second embodiment of thepresent invention;

FIG. 5 is a partially enlarged front view of a combination read/writethin film magnetic head in accordance with a third embodiment of thepresent invention;

FIG. 6 is a partially enlarged front view of a combination read/writethin film magnetic head in accordance with a fourth embodiment of thepresent invention;

FIG. 7 is a partially enlarged front view of a combination read/writethin film magnetic head in accordance with a fifth embodiment of thepresent invention;

FIG. 8 is a partially enlarged front view of a combination read/writethin film magnetic head in accordance with a sixth embodiment of thepresent invention;

FIG. 9 is a graph showing the relations between the thickness L1 of theshielding magnetic layer 4 and the write fringing amount and between thethickness L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 5 is formed by using a Co-Fe-Ni alloy;

FIG. 10 is a graph showing the relations between the thickness L1 of theshielding magnetic layer 4 and the write fringing amount and between thethickness L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 5 is formed by using a Ni-Fe alloy;

FIG. 11 is a graph showing the relations between the thickness L1 of theshielding magnetic layer 4 and the write fringing amount and between thethickness L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 5 is formed by using a Co-Zr-Nb alloy;

FIG. 12 is a graph showing the relations between the saturation magneticflux density Bs•the thickness L1 and the write fringing amount andbetween Bs•L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 3 is formed by using a Ni-Fe alloy;

FIG. 13 is a graph showing the relations between the saturation magneticflux density Bs•the thickness L1 and the write fringing amount andbetween Bs•L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 4 is formed by using a Ni-Fe alloy;

FIG. 14 is a graph showing the relations between the saturation magneticflux density Bs•the thickness L1 and the write fringing amount andbetween Bs•L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 5 is formed by using a Ni-Fe alloy;

FIG. 15 is a graph showing the relations between the saturation magneticflux density Bs•the thickness L1 and the write fringing amount andbetween Bs•L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 7 is formed by using a Ni-Fe alloy;

FIG. 16 is a graph showing the relations between the saturation magneticflux density Bs•the thickness L1 and the write fringing amount andbetween Bs•L1 and over write performance when the shielding magneticlayer 4 of the combination read/write thin film magnetic head shown inFIG. 8 is formed by using a Ni-Fe alloy;

FIG. 17 is a half sectional perspective view showing the shapes of alower core layer and an upper core layer of a conventional combinationread/write thin film magnetic head; and

FIG. 18(A) is a partially enlarged front view as viewed from the frontside of a conventional combination read/write thin film magnetic head,and FIG. 18(B) is a drawing showing the image of a record patternrecorded on a recording medium by using the magnetic head shown in FIG.18(A).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 is a longitudinal sectional view showing a writing inductive headof a combination read/write thin film magnetic head of the presentinvention, and FIG. 3 is a partial front view showing a portion of thecombination read/write thin film magnetic head shown in FIG. 2 oppositeto a recording medium, as viewed from an arrow II of FIG. 2.

Referring to FIGS. 2 and 3, the writing inductive head comprises a lowercore layer 1 and an upper core layer 3, which are made of a softmagnetic material having high magnetic permeability such as an Ni-Fealloy (permalloy) or the like. As shown in FIG. 1, a reading head whichcomprises a magnetoresistive element layer 13 and a lower shieldinglayer 14 and which employs magnetoresistance is provided below the lowercore layer 1 so that the lower core layer 1 also serves as an uppershielding layer for the magnetoresistive element layer 13. In order toenable stable formation of a coil layer 5 above the lower core layer 1,the lower core layer 1 is formed with a sufficiently large width T2 sothat the lower core layer 1 can sufficiently exhibit the function as theupper shielding layer for the magnetoresistive element layer 13.

The magnetoresistive element layer 13 comprises, for example, a laminateof a soft magnetic layer (soft adjacent layer SAL), a non-magnetic layer(SHUNT layer) and a magnetoresistive layer (MR layer). On both sides ofthe magnetoresistive element layer 13 are provided a hard bias layer forapplying a longitudinal bias magnetic field, and a main lead layer forapplying a sensing current.

A non-magnetic material layer 2 is formed over the whole upper surfaceof the lower core layer 1. However, in a portion with the gap depth L4shown in FIG. 2, the non-magnetic material layer 2 is left as a gaplayer 2a in a portion where the lower core layer 1 and the tip 3a of theupper core layer 3 are opposite to each other, and the non-magneticmaterial layer 2 is removed in a portion where the lower core layer 1and the tip 3a of the upper core layer 3 are not opposite to each other.The tip 3a of the upper core layer 3 is joined to the lower core layer 1with the gap layer 2a therebetween.

In the combination read/write thin film magnetic head shown in FIG. 3,both the width of the upper surface 2a1 of the gap layer 2a whichcontacts the tip 3a of the upper core layer 3 and the width T1 of thelower surface 2a2 of the gap layer 2a which contacts the lower corelayer are the same as the width Tw of the tip 3a.

The non-magnetic material layer 2 can be formed by sputtering. However,in the magnetic head shown in FIG. 3, the non-magnetic material layercan be removed by chemical function of plasma etching, and is made of amaterial which does not damage the soft magnetic material (for example,permalloy), which forms the lower core layer 1, in the plasma etchingstep. The non-magnetic material is, for example, a single layer film ofSiO₂, Ta₂ O₅, Si₃ N₄, TiO, Ti₂ O₃, Ti₃ O₅, TiO₂ or WO₃, or a compositeor multilayer film comprising at least two films thereof.

On the non-magnetic material layer 2 is formed an insulation layer 6 ofa resist material, e.g., an organic resin material. On the insulationlayer 6 is formed a coil layer 5 by using a electrically conductivematerial having low electric resistance, such as Cu or the like. Thecoil layer 5 is spirally formed in a plane around the base end 3b of theupper core layer 3. On the coil layer 5 is formed an insulation layer 7comprising an organic resin layer to cover the coil layer 5.

On the insulation layer 7 is formed the upper core layer 3 by theplating process. The upper core layer 3 comprises a magnetic materialsuch as permalloy or the like, the tip 3a thereof being joined to theopposite surface of the lower core layer 1 with the gap layer 2atherebetween to form a magnetic gap having a gap length G1. The trackwidth of the magnetic gap is determined by the width Tw of the tip 3a ofthe upper core layer 3. The base end 3b of the upper core layer 3 ismagnetically connected to the lower core layer 1.

A shielding magnetic layer 4 made of a soft magnetic material isdeposited by sputtering over a portion extending from both sides of thegap layer 2a in the direction of the track width to the upper surface ofthe tip 3a of the upper core layer. However, the average thickness L1 ofthe shielding magnetic layer 4 is preferably within the range of 0.001to 1.0 μm.

Particularly, when the saturation magnetic flex density Bs of theshielding magnetic layer is 0.95 T or less, the thickness L1 of theshielding magnetic layer is more preferably within the range of 0.05 to1.0 μm. When the saturation magnetic flex density Bs of the shieldingmagnetic layer is 0.95 to 1.8 T, the thickness L1 of the shieldingmagnetic layer is more preferably within the range of 0.01 to 0.4 μm.When the saturation magnetic flex density Bs of the shielding magneticlayer is 1.8 T or more, the thickness L1 of the shielding magnetic layeris more preferably within the range of 0.001 to 0.4 μm.

The upper core layer 3 is covered with a protective layer (not shown)made of a non-magnetic material such as aluminum oxide or the like.

In this inductive head, when a recording current is supplied to the coillayer 5, a record magnetic field is induced in the lower core layer 1and the upper core layer 3, and a magnetic signal is recorded on arecording medium such as a hard disk or the like by a leakage magneticfield between the lower core layer 1 and the tip 3a of the upper corelayer 3 in the portion with the gap length G1.

Also, in the inductive head, the width of the gap layer 2a issubstantially the same as the track width Tw, and the shielding magneticlayer 4 of a soft magnetic material is formed on both sides of the gaplayer 2a. Therefore, blots of the record magnetic field out of the trackwidth Tw are absorbed by the shielding magnetic layer 4, and thus writefringing can be suppressed. Since the write fringing can effectively besuppressed, it is possible to perform recording with a very short trackpitch and high density recording.

Particularly, when the shielding magnetic layer 4 is formed in thethickness L1 which satisfies the above conditions, it is possible tosuppress write fringing and, at the same time, maintain the over writeperformance at a high level during recording.

The method of manufacturing the combination read/write thin filmmagnetic head shown in FIG. 3 will be described below.

First, a soft magnetic material with high magnetic permeability, such aspermalloy, is plated to form the lower core layer 1 having a rectangularfront side having a width T2, as shown in FIG. 3. Next, the non-magneticmaterial layer 2 is formed over the whole upper surface of the lowercore layer 1. As the non-magnetic material, a material which does notdamage the soft magnetic material of the lower core layer 1 in theplasma etching step with CF₄ or CF₄ and oxygen (O₂) is selected. Asuitable non-magnetic material is a single layer film of SiO₂, Ta₂ O₅,Si₃ N₄, TiO, Ti₂ O₃, Ti₃ O₅, TiO₂ or WO₃, or a composite or multilayerfilm comprising at least two films thereof.

To the non-magnetic material layer 2 is joined the tip 3a of the uppercore layer 3 of a magnetic material having the width Tw. The upper corelayer 3 is formed on the insulation layer 7 shown in FIG. 2 by plating.This step comprises forming a resist pattern in a portion other than theregion where the upper core layer 3 is formed, plating the soft magneticmaterial on a portion without the resist pattern formed, and thenremoving the resist material. As a result, the tip 3a of the upper corelayer 3 is formed with the width Tw.

Next, portions of the non-magnetic material layer 2 on both sides of thegap layer 2a are removed by plasma etching, leaving as the gap layer 2athe non-magnetic material layer 2 interposed between the tip 3a of theupper core layer 3 and the lower core layer 1.

The plasma etching is carried out with unidirectionality only in thedirection of an arrow R. Therefore, the gap layer 2a interposed betweenthe tip 3a and the lower core layer 1 is not affected by the plasmaetching and left with the width Tw (=T1) between the tip 3a and thelower core layer 1. The plasma etching is performed for removing thenon-magnetic material by chemical function, and thus the magneticmaterial which forms the lower core layer 1 is not damaged by the plasmaetching.

Next, the shielding magnetic layer 4 made of a soft magnetic material isdeposited by sputtering over a portion extending from the both sides ofthe gap layer 2a in the direction of the track width to the uppersurface of the tip 3a of the upper core layer 3. The soft magneticmaterial which forms the shielding magnetic layer 4 may be the same asor different from the soft magnetic material which forms the lower corelayer 1. However, the shielding magnetic layer 4 must be formed so thatthe thickness L1 thereof satisfies the above conditions.

FIGS. 4 to 6 show modified examples of the shielding magnetic layer 4formed by sputtering.

In the thin film magnetic head shown in FIG. 4, a portion of thenon-magnetic material layer 2 other than the gap layer 2b interposedbetween the tip 3a of the upper core layer 3 and the lower core layer 1is removed by ion-milling. By using ion-milling in place of plasmaetching, inclined portions 2' are formed on both sides of the gap layer2b, and the width T1 of the lower surface 2b2 of the gap layer 2b whichcontacts the lower core layer 1 is slightly longer than the width of theupper surface 2bl of the gap layer 2b which contacts the tip 3a of theupper core layer 3.

In the ion-milling, neutral ions of Ar (argon) gas are used, thenon-magnetic material layer 2 formed on the lower core layer 1 isirradiated with the ions in directions of inclined arrows S and T toremove a portion of the non-magnetic material layer 2 other than the gaplayer 2b interposed between the tip 3a and the lower core layer 1, byphysical function. At the same time, the inclined portions 2' are formedon both sides of the gap layer 2b in the direction of the track width toform the gap layer 2b having a trapezoidal front side.

If the strength of ion-milling is increased, the lower core layer 1 of asoft magnetic material is also affected by the ion milling. As a result,the lower core layer 1 is removed to a depth L2 to form, in the lowercore layer 1, inclined surfaces 1' which respectively continue from theinclined portions 2' of the gap layer 2b, as in the thin film magnetichead shown in FIG. 5.

When the gap layer 2b is formed by the ion-milling, since the width T1of the lower surface 2b2 of the gap layer 2b which contacts the lowercore layer 1 is slightly longer than the track width tw, as shown inFIGS. 4 and 5, blots of the record magnetic field easily occur out ofthe track width Tw. However, the effect of preventing fringing can beobtained by forming the shielding magnetic layer 4. Particularly, whenthe shielding magnetic layer 4 is formed to the thickness L1 whichsatisfies the above conditions, the amount of write fringing can bedecreased, and at the same time, the over write performance can bemaintained at a high level during recording.

Also, when the gap layer 2b is formed by the ion-milling, aluminum oxideor the like, which is conventionally used, can be used as thenon-magnetic material. Namely, unlike the case of plasma etching shownin FIG. 3, the non-magnetic material layer 2 need not be formed by usinga material suitable for plasma etching, thereby widening the selectivityof materials.

In the combination read/write thin film magnetic head shown in FIG. 6, aportion of the non-magnetic material layer 2 other than the gap layer 2ainterposed between the tip 3a of the upper core layer 3 and the lowercore layer 1 is removed by plasma etching, and the lower core layer 1 isremoved by the thickness L2 by ion-milling. The shielding magnetic layer4 is formed by a deposition process such as sputtering. Therefore, theupper surface 2a1 and the lower surface 2a2 of the gap layer 2a have thesame width, and inclined surfaces 1' are formed only in the lower corelayer 1 to form a trapezoidal front side.

FIGS. 7 and 8 show a method comprising removing the lower core layer 1by the thickness L3 by ion-milling, and readhering the removed magneticmaterial to both sides of the gap layer to form a shielding magneticlayer 4a.

In the combination read/write thin film magnetic head shown in FIG. 7,the non-magnetic material layer 2 is removed by ion-milling in thedirections of arrows S and T to form the gap layer 2b between the tip 3aof the upper core layer 3 and the lower core layer 1. At the same time,inclined portions 2' are formed on both sides of the gap layer 2b, thewidth T1 being slightly longer than the track width Tw. At this time,the non-magnetic material removed from a portion other than the gaplayer 2b is readhered to both sides of the tip 3a of the upper corelayer 3 to form readhered thin layers 2".

Further, the lower core layer is removed by the thickness L3 in anion-milling step continued from the step of removing the non-magneticmaterial layer 2 or a separate ion-milling step to form the inclinedsurfaces 1' in the lower core layer 1. The removed soft magneticmaterial having the thickness L3 is readhered to the vicinities of bothsides of the gap layer 2b and to the surfaces of the readhered layers2', to form the shielding magnetic layers 4a.

In the combination read/write thin film magnetic head shown in FIG. 8,the non-magnetic material layer 2 is removed by plasma etching to formthe gap layer 2a having the same width L1 as the track width Tw. Next,the lower core layer 1 is removed by the thickness L3 by ion-milling,and the soft magnetic material removed from the lower core layer by thethickness L3 is readhered to both sides of the gap layer 2 to form theshielding magnetic layers 4a.

When the shielding magnetic layers 4a are formed by readhesion, thematerial of the shielding magnetic layers 4a is the same as the lowercore layer 1.

It is necessary for the shielding magnetic layers 4a shown in FIGS. 7and 8 to satisfy at least the conditions of the thickness L1 of theshielding magnetic layer 4 of the thin film magnetic head shown in FIG.3.

When the shielding magnetic layers 4a are formed by readhesion, thethickness L1 of the shielding magnetic layers 4a is determined by theamount of the soft magnetic material removed from the lower core layerto the thickness L3 by ion-milling, and thus the soft magnetic materialhaving the thickness L3 must be removed so that the thickness L1 of theshielding magnetic layers 4a satisfies the above-described conditions.This is determined by the milling time and the degree of vacuum.

In the inductive head where the shielding magnetic layers 4a are formedby readhesion, like the inductive head where the shielding magneticlayer 4 is formed by deposition, since blots of the record magneticfield occur out of the track width Tw is absorbed by the shieldingmagnetic layer 4a, it is possible to suppress write fringing, and at thesame time, maintain the over write performance at a high level.

EXAMPLES

Description will be made of examples of the combination read/write thinfilm magnetic head where the shielding magnetic layer is formed on bothsides of the gap layer.

The relation between the thickness L1 of the shielding magnetic layer 4and the fringing amount and the relation between the thickness L1 of theshielding magnetic layer 4 and over write performance were examined byusing the combination read/write thin film magnetic head shown in FIG.5.

The manufacturing method and the shape of the combination read/writethin film magnetic head shown in FIG. 5 have the followingcharacteristics:

(1) The shielding magnetic layer 4 is formed by sputtering.

(2) The soft magnetic material of the lower core layer 1 is removed bythe thickness L2 by ion-milling to form the inclined portions 1'.

(3) The gap layer 2a has the inclined portions 2', and is formed so thatthe width T1 of the lower surface 2b2 thereof which contacts the lowercore layer 1 is slightly longer than the track width Tw.

FIG. 9 shows the results of experiment using a Co-Fe-Ni(cobalt-iron-nickel) alloy for the shielding magnetic layer 4, theCo-Fe-Ni alloy having a saturation magnetic flux density Bs of 1.8 T(tesla).

FIG. 10 shows the results of experiment using a Ni-Fe (nickel-iron)alloy for the shielding magnetic layer 4, the Ni-Fe alloy having asaturation magnetic flux density Bs of 0.95 T (tesla).

FIG. 11 shows the results of experiment using a Co-Zr-Nb(cobalt-zirconium-niobium) alloy for the shielding magnetic layer 4, theCo-Zr-Nb alloy having a saturation magnetic flux density Bs of 0.5 T(tesla).

In the drawings, a curve formed by open circle marks O shows therelation between the thickness L1 of the shielding magnetic layer 4 andthe fringing amount, and a curve formed by black dot marks • shows therelation between the thickness L1 of the shielding magnetic layer 4 andover write performance (dB) during recording. The fringing amount (μm)means the length obtained by subtracting the track width Tw from thelength TF of the record pattern of magnetic data recorded on a recordingmedium. The over write performance means the reproduced output valueafter magnetic data has been recorded on the recording medium.

FIGS. 9 to 11 indicate that as the thickness L1 (μm) of the shieldingmagnetic layer 4 increases, the fringing amount (μm) decreases, and atthe same time, the over write performance (dB) also deteriorates.

This is possibly caused by the phenomenon that as the thickness (μm) ofthe shielding magnetic layer 4 increases, blots of the record magneticfield occur out of the track width Tw is easily absorbed by theshielding magnetic layer 4, and thus the fringing amount (μm) decreases.However, at the same time, the effective record magnetic field producedin the track width is also easily absorbed by the shielding magneticlayer 4, and thus the over write performance (dB) possibly deteriorates.

It is also found that even with a small thickness L1, the fringingamount can be decreased by increasing the saturation magnetic fluxdensity Bs, and the over write performance can be maintained at a highlevel with a smaller thickness L1.

Preferably, the absolute value of the over write performance (dB) is 32dB or more, and the fringing amount (μm) is 0.28 μm or less. When thethickness L1 corresponding to these ranges is determined from thedrawings, in the use of the Co-Fe-Ni alloy having maximum Bs, the Ni-Fealloy and the Co-Zr-Nb alloy having minimum Bs, the thickness L1 is 0.01to 0.19 μm or 0.01 to 0.2 μm, 0.05 to 0.38 μm or 0.05 to 0.4 μm and 0.2to 0.73 μm, respectively.

More preferably, the absolute value of the over write performance (dB)is 32 dB or more, and the fringing amount (μm) is 0.25 μm or less. Whenthe thickness L1 corresponding to these ranges is determined from thedrawings, in the use of the Co-Fe-Ni alloy having maximum Bs, the Ni-Fealloy and the Co-Zr-Nb alloy having minimum Bs, the thickness L1 is 0.05to 0.19 μm or 0.05 to 0.2 μm, 0.1 to 0.38 μm or 0.1 to 0.4 μm and thethickness L1 is 0.3 to 0.73 μm, respectively.

More preferably, the absolute value of the over write performance (dB)is 32 dB or more, and the fringing amount (μm) is 0.2 μm or less. Whenthe thickness L1 corresponding to these ranges is determined from thedrawings, in the use of the Co-Fe-Ni alloy having maximum Bs, the Ni-Fealloy and the Co-Zr-Nb alloy having minimum Bs, the thickness L1 is 0.1to 0.19 μm or 0.1 to 0.2 μm, 0.2 to 0.38 μm or 0.2 to 0.4 μm and thethickness L1 is 0.4 to 0.73 μm, respectively.

More preferably, the absolute value of the over write performance (dB)is 32 dB or more, and the fringing amount (μm) is 0.15 μm or less. Whenthe thickness L1 corresponding to these ranges is determined from thedrawings, in the use of the Co-Fe-Ni alloy having maximum Bs, the Ni-Fealloy and the Co-Zr-Nb alloy having minimum Bs, the thickness L1 is 0.13to 0.19 μm or 0.13 to 0.2 μm, 0.25 to 0.38 μm or 0.25 to 0.4 μm and thethickness L1 is 0.47 to 0.73 μm, respectively.

Most preferably, the absolute value of the over write performance (dB)is 32 dB or more, and the fringing amount (μm) is 0.1 μm or less. Whenthe thickness L1 corresponding to these ranges is determined from thedrawings, in the use of the Co-Fe-Ni alloy having maximum Bs, the Ni-Fealloy and the Co-Zr-Nb alloy having minimum Bs, the thickness L1 is 0.15to 0.19 μm or 0.15 to 0.2 μm, 0.3 to 0.38 μm or 0.3 to 0.4 μm and thethickness L1 is 0.53 to 0.73 μm, respectively.

It can be understood from FIGS. 10 and 11 that if the Bs value of 0.95 Tof the Ni-Fe alloy is considered as a mean value, when the Bs is 0.95 Tor less, the thickness L1 of the shielding magnetic layer is preferablyappropriately selected within the range of 0.05 to 1.0 μm in order toachieve an absolute value of over write performance (dB) of 32 dB ormore and a fringing amount (μm) of 0.28 μm or less.

It can also be understood from FIGS. 10 and 11 that in order to achievean absolute value of over write performance (dB) of 32 dB or more, and afringing amount (μm) of 0.25 μm or less, the thickness L1 of theshielding magnetic layer is preferably appropriately selected within therange of 0.1 to 1.0 μm.

It can further be understood from FIGS. 10 and 11 that in order toachieve an absolute value of over write performance (dB) of 32 dB ormore, and a fringing amount (μm) of 0.2 μm or less, the thickness L1 ofthe shielding magnetic layer is preferably appropriately selected withinthe range of 0.2 to 1.0 μm.

It can further be understood from FIGS. 10 and 11 that in order toachieve an absolute value of over write performance (dB) of 32 dB ormore, and a fringing amount (μm) of 0.15 μm or less, the thickness L1 ofthe shielding magnetic layer is preferably appropriately selected withinthe range of 0.25 to 1.0 μm.

It can further be understood from FIGS. 10 and 11 that in order toachieve an absolute value of over write performance (dB) of 32 dB ormore, and a fringing amount (μm) of 0.1 μm or less, the thickness L1 ofthe shielding magnetic layer is preferably appropriately selected withinthe range of 0.3 to 1.0 μm.

It can be understood from FIGS. 9 and 10 that when Bs is 0.95 T or more,in order to achieve an absolute value of over write performance (dB) of32 dB or more, and a fringing amount (μm) of 0.28 μm or less, thethickness L1 of the shielding magnetic layer is preferably appropriatelyselected within the range of 0.01 to 0.4 μm.

It can also be understood from FIGS. 9 and 10 that in order to achievean absolute value of over write performance (dB) of 32 dB or more, and afringing amount (μm) of 0.25 μm or less, the thickness L1 of theshielding magnetic layer is preferably appropriately selected within therange of 0.05 to 0.4 μm.

It can further be understood from FIGS. 9 and 10 that in order toachieve an absolute value of over write performance (dB) of 32 dB ormore, and a fringing amount (μm) of 0.2 μm or less, the thickness L1 ofthe shielding magnetic layer is preferably appropriately selected withinthe range of 0.1 to 0.4 μm.

It can further be understood from FIGS. 9 and 10 that in order toachieve an absolute value of over write performance (dB) of 32 dB ormore, and a fringing amount (μm) of 0.15 μm or less, the thickness L1 ofthe shielding magnetic layer is preferably appropriately selected withinthe range of 0.13 to 0.4 μm.

It can further be understood from FIGS. 9 and 10 that in order toachieve an absolute value of over write performance (dB) of 32 dB ormore, and a fringing amount (μm) of 0.1 μm or less, the thickness L1 ofthe shielding magnetic layer is preferably appropriately selected withinthe range of 0.15 to 0.4 μm.

Influences of the thickness L1 on the fringing amount (m) and the overwrite performance (dB) were examined by using a Ni-Fe alloy for thelower core layer 1 and the shielding magnetic layer 4 (or 4a), whilechanging the thickness L1. The Ni-Fe alloy had a saturation magneticflux density Bs of 0.95 T (tesla).

The following five types of combination read/write thin film magneticheads were used as the combination read/write thin film magnetic head,and several combination read/write thin film magnetic heads havingdifferent thicknesses L1 were manufactured for each of the types ofcombination read/write thin film magnetic heads, and subjected toexperiment.

The characteristics of the five types of combination read/write thinfilm magnetic heads will be described below.

(1) Combination read/write thin film magnetic head shown in FIG. 3(referred to as "Type A" hereinafter)

(Characteristic)

The shielding magnetic layer 4 is deposited.

The gap layer 2a is formed by plasma etching.

(2) Combination read/write thin film magnetic head shown in FIG. 4(referred to as "Type B" hereinafter)

(Characteristic)

The shielding magnetic layer 4 is deposited.

The gap layer 2a is formed by ion-milling.

(3) Combination read/write thin film magnetic head shown in FIG. 5(referred to as "Type C" hereinafter)

(Characteristic)

The shielding magnetic layer 4 is deposited.

The gap layer 2a is formed by ion-milling.

The inclined surfaces 1' are formed in the lower core layer 1 byion-milling.

(4) Combination read/write thin film magnetic head shown in FIG. 7(referred to as "Type D" hereinafter)

(Characteristic)

The shielding magnetic layer 4a is formed by readhesion.

The gap layer 2a is formed by ion-milling.

The inclined surfaces 1' are formed in the lower core layer 1 byion-milling.

(5) Combination read/write thin film magnetic head shown in FIG. 8(referred to as "Type E" hereinafter)

(Characteristic)

The shielding magnetic layer 4a is formed by readhesion.

The gap layer 2a is formed by plasma etching.

The inclined surfaces 1' are formed in the lower core layer 1 byion-milling.

FIGS. 12, 13, 14, 15 and 16 are graphs showing experimental results withType A, Type B, Type C, Type D and Type E, respectively. In FIGS. 12 to16, a curve formed by open circle marks O shows the relation between L1and the fringing amount (μm), and a curve formed by black dot marks •shows the relation between L1 and the over write performance (dB).

It can be found that in all figures, if L1 is within the range of 0.05to 0.48 μm, the fringing amount (μm) can be suppressed to some extent,and at the same time, the over write performance (dB) can be maintainedat a high level to some extent.

Preferably, the absolute value of over write performance (dB) is 32 dBor more, and the fringing amount is 0.28 μm or less. When L1corresponding to these ranges is determined from each of the figures, L1of Type A shown in FIG. 12 is 0.2 to 0.38 μm, L1 of Type B shown in FIG.13 is 0.17 to 0.37 μm, L1 of Type C shown in FIG. 14 is 0.05 to 0.38 μm,L1 of Type D shown in FIG. 15 is 0.28 to 0.48 μm, and L1 of Type E shownin FIG. 16 is 0.1 to 0.37 μm.

More preferably, the absolute value of over write performance (dB) is 32dB or more, and the fringing amount is 0.25 μm or less. When L1corresponding to these ranges is determined from each of the figures, L1of Type A shown in FIG. 12 is 0.21 to 0.38 μm, L1 of Type B shown inFIG. 13 is 0.2 to 0.37 μm, L1 of Type C shown in FIG. 14 is 0.1 to 0.38μm, L1 of Type D shown in FIG. 15 is 0.3 to 0.48 μm, and L1 of Type Eshown in FIG. 16 is 0.15 to 0.37 μm.

More preferably, the absolute value of over write performance (dB) is 32dB or more, and the fringing amount is 0.2 μm or less. When L1corresponding to these ranges is determined from each of the figures, L1of Type A shown in FIG. 12 is 0.24 to 0.38 μm, L1 of Type B shown inFIG. 13 is 0.24 to 0.37 μm, L1 of Type C shown in FIG. 14 is 0.2 to 0.38μm, L1 of Type D shown in FIG. 15 is 0.34 to 0.48 μm, and L1 of Type Eshown in FIG. 16 is 0.21 to 0.37 μm.

More preferably, the absolute value of over write performance (dB) is 32dB or more, and the fringing amount is 0.15 μm or less. When L1corresponding to these ranges is determined from each of the figures, L1of Type A shown in FIG. 12 is 0.25 to 0.38 μm, L1 of Type B shown inFIG. 13 is 0.27 to 0.37 μm, L1 of Type C shown in FIG. 14 is 0.25 to0.38 μm, L1 of Type D shown in FIG. 15 is 0.39 to 0.48 μm, and L1 ofType E shown in FIG. 16 is 0.25 to 0.37 μm.

Most preferably, the absolute value of over write performance (dB) is 32dB or more, and the fringing amount is 0.1 μm or less. When L1corresponding to these ranges is determined from each of the figures, L1of Type A shown in FIG. 12 is 0.26 to 0.38 μm, L1 of Type B shown inFIG. 13 is 0.3 to 0.37 μm, L1 of Type C shown in FIG. 14 is 0.3 to 0.38μm, L1 of Type D shown in FIG. 15 is 0.45 to 0.48 μm, and L1 of Type Eshown in FIG. 16 is 0.3 to 0.37 μm.

Therefore, it is understood that when a Ni-Fe alloy is used for theshielding magnetic layer, the thickness L1 of the shielding magneticlayer is preferably appropriately selected within the range of 0.05 to0.48 μm in order to achieve an absolute value of over write performance(dB) of 32 dB or more, and a fringing amount of 0.28 μm or less.

It is also understood that the thickness L1 of the shielding magneticlayer is preferably appropriately selected within the range of 0.1 to0.48 μm in order to achieve an absolute value of over write performance(dB) of 32 dB or more, and a fringing amount of 0.25 μm or less.

It is further understood that the thickness L1 of the shielding magneticlayer is preferably appropriately selected within the range of 0.2 to0.48 μm in order to achieve an absolute value of over write performance(dB) of 32 dB or more, and a fringing amount of 0.2 μm or less.

It is further understood that the thickness L1 of the shielding magneticlayer is preferably appropriately selected within the range of 0.25 to0.48 μm in order to achieve an absolute value of over write performance(dB) of 32 dB or more, and a fringing amount of 0.15 μm or less.

It is further understood that the thickness L1 of the shielding magneticlayer is preferably appropriately selected within the range of 0.26 to0.48 μm in order to achieve an absolute value of over write performance(dB) of 32 dB or more, and a fringing amount of 0.1 μm or less.

As described above, in the present invention, the shielding magneticlayer made of a soft magnetic material is provided on both sides of thegap layer so that blots of the record magnetic field out of the trackwidth can be absorbed by the shielding magnetic layer, and writefringing can be prevented. Particularly, when the shielding magneticlayer is formed with the saturation magnetic flux density and thethickness appropriately adjusted, it is possible to suppress writefringing and at the same time, maintain reproduced output at a highlevel.

Also the manufacturing method of the present invention is capable offorming the shielding magnetic layer by removing the lower core layerand readhering the removed soft magnetic material to both sides of thegap layer, thereby facilitating manufacture.

What is claimed is:
 1. A combination read/write thin film magnetic headcomprising:a lower core layer of a magnetic material; an upper corelayer of a magnetic material provided opposite to the lower core layerand having a width smaller than that of the lower core layer; a gaplayer interposed between and in contact with the lower core layer andthe upper core layer; a coil layer for inducing a record magnetic fieldin the lower core layer and the upper core layer; and a shieldingmagnetic layer of a soft magnetic material coated on both sides of thegap layer in the direction of the track width as well and on said lowercore layer.
 2. A combination read/write thin film magnetic headaccording to claim 1, wherein the width Tw of the upper core layer inthe direction of the track width is the same as the width of the uppersurface of the gap layer which contacts the upper core layer and thewidth T1 of the lower surface of the gap layer which contacts the lowercore layer.
 3. A combination read/write thin film magnetic headaccording to claim 2, wherein the average thickness L1 of the shieldingmagnetic layer is within the range of 0.001 to 1.0 μm.
 4. A combinationread/write thin film magnetic head according to claim 2, wherein whenthe saturation magnetic flux density Bs of the shielding magnetic layeris no more than about 0.95 T, and the thickness L1 of the shieldingmagnetic layer is within the range of 0.05 to 1.0 :m.
 5. A combinationread/write thin film magnetic head according to claim 4, wherein whenthe saturation magnetic flux density B_(s) of the shielding magneticlayer is within the range of about 0.5 T to 0.95 T and the thickness L1of the shielding magnetic layer is within the range of 0.5 to 1.0 :m. 6.A combination read/write thin film magnetic head according to claim 2,wherein when the saturation magnetic flux density Bs of the shieldingmagnetic layer is 0.95 T to 1.8 T, the thickness L1 of the shieldingmagnetic layer is within the range of 0.01 to 0.4 μm.
 7. A combinationread/write thin film magnetic head according to claim 2, wherein whenthe saturation magnetic flux density Bs of the shielding magnetic layeris at least about 1.8 T, and the thickness L1 of the shielding magneticlayer is within the range of 0.001 to 0.4 :m.
 8. A combinationread/write thin film magnetic head according to claim 2, wherein whenthe shielding magnetic layer is formed of a Ni-Fe (nickel-iron) alloy,the thickness L1 of the shielding magnetic layer is within the range of0.05 to 0.48 μm.
 9. A combination read/write thin film magnetic headaccording to claim 2, wherein when the shielding magnetic layer isformed of a Ni-Fe (nickel-iron) alloy, the thickness L1 of the shieldingmagnetic layer is within the range of 0.05 to 0.4 μm.
 10. A combinationread/write thin film magnetic head according to claim 2, wherein whenthe shielding magnetic layer is formed of a Co-Zr-Nb(cobalt-zirconium-niobium) alloy, the thickness L1 of the shieldingmagnetic layer is within the range of 0.2 to 0.73 μm.
 11. A combinationread/write thin film magnetic head according to claim 2, wherein whenthe shielding magnetic layer is formed of a Co-Fe-Ni(cobalt-iron-nickel) alloy, the thickness L1 of the shielding magneticlayer is within the range of 0.01 to 0.2 μm.
 12. A combinationread/write thin film magnetic head according to claim 1, wherein the gaplayer is formed so that the width in the direction of the track widthgradually increases from the upper surface in contact with the uppercore layer to the lower surface in contact with the lower core layer.13. A combination read/write thin film magnetic head according to claim12, wherein the average thickness L1 of the shielding magnetic layer iswithin the range of 0.001 to 1.0 μm.
 14. A combination read/write thinfilm magnetic head according to claim 12, wherein when the saturationmagnetic flux density Bs of the shielding magnetic layer is no more thanabout 0.95 T, and the thickness L1 of the shielding magnetic layer iswithin the range of 0.05 to 1.0 :m.
 15. A combination read/write thinfilm magnetic head according to claim 14, wherein when the saturationmagnetic flux density B_(s) of the shielding magnetic layer is about 0.5T to 0.95 T, and the thickness L1 of the shielding magnetic layer iswithin the range of 0.05 to 1.0 :m.
 16. A combination read/write thinfilm magnetic head according to claim 12, wherein when the saturationmagnetic flux density Bs of the shielding magnetic layer is 0.95 T to1.8 T, the thickness L1 of the shielding magnetic layer is within therange of 0.01 to 0.4 μm.
 17. A combination read/write thin film magnetichead according to claim 12, wherein when the saturation magnetic fluxdensity Bs of the shielding magnetic layer is at least about 1.8 T, andthe thickness L1 of the shielding magnetic layer is within the range of0.001 to 0.4 :m.
 18. A combination read/write thin film magnetic headaccording to claim 12, wherein when the shielding magnetic layer isformed of a Ni-Fe (nickel-iron) alloy, the thickness L1 of the shieldingmagnetic layer is within the range of 0.05 to 0.48 μm.
 19. A combinationread/write thin film magnetic head according to claim 12, wherein whenthe shielding magnetic layer is formed of a Ni-Fe (nickel-iron) alloy,the thickness L1 of the shielding magnetic layer is within the range of0.05 to 0.4 μm.
 20. A combination read/write thin film magnetic headaccording to claim 12, wherein when the shielding magnetic layer isformed of a Co-Zr-Nb (cobalt-zirconium-niobium) alloy, the thickness L1of the shielding magnetic layer is within the range of 0.2 to 0.73 μm.21. A combination read/write thin film magnetic head according to claim12, wherein when the shielding magnetic layer is formed of a Co-Fe-Ni(cobalt-iron-nickel) alloy, the thickness L1 of the shielding magneticlayer is within the range of 0.01 to 0.2 μm.
 22. A combinationread/write thin film magnetic head according to claim 1, wherein theaverage thickness L1 of the shielding magnetic layer is within the rangeof 0.001 to 1.0 μm.
 23. A combination read/write thin film magnetic headaccording to claim 1, wherein when the saturation magnetic flux densityBs of the shielding magnetic layer is no more than about 0.95 T, and thethickness L1 of the shielding magnetic layer is within the range of 0.05to 1.0 :m.
 24. A combination read/write thin film magnetic headaccording to claim 23, wherein when the saturation magnetic flux densityB_(s) of the shielding magnetic layer is about 0.5 T to 0.95 T, and thethickness L1 of the shielding magnetic layer is within the range of 0.05to 1.0 :m.
 25. A combination read/write thin film magnetic headaccording to claim 1, wherein when the saturation magnetic flux densityBs of the shielding magnetic layer is 0.95 T to 1.8 T, the thickness L1of the shielding magnetic layer is within the range of 0.01 to 0.4 μm.26. A combination read/write thin film magnetic head according to claim1, wherein when the saturation magnetic flux density Bs of the shieldingmagnetic layer is at least about 1.8 T, and the thickness L1 of theshielding magnetic layer is within the range of 0.001 to 0.4 :m.
 27. Acombination read/write thin film magnetic head according to claim 1,wherein when the shielding magnetic layer is formed of a Ni-Fe(nickel-iron) alloy, the thickness L1 of the shielding magnetic layer iswithin the range of 0.05 to 0.48 μm.
 28. A combination read/write thinfilm magnetic head according to claim 1, wherein when the shieldingmagnetic layer is formed of a Ni-Fe (nickel-iron) alloy, the thicknessL1 of the shielding magnetic layer is within the range of 0.05 to 0.4μm.
 29. A combination read/write thin film magnetic head according toclaim 1, wherein when the shielding magnetic layer is formed of aCo-Zr-Nb (cobalt-zirconium-niobium) alloy, the thickness L1 of theshielding magnetic layer is within the range of 0.2 to 0.73 μm.
 30. Acombination read/write thin film magnetic head according to claim 1,wherein when the shielding magnetic layer is formed of a Co-Fe-Ni(cobalt-iron-nickel) alloy, the thickness L1 of the shielding magneticlayer is within the range of 0.01 to 0.2 μm.